Astronomers Discover Metal-Poor Globular Cluster by Chance 15 October 2020

Astronomers discover metal-poor globular cluster by chance 15 October 2020

The researchers made their observations with the HIRES spectrometer of the Keck Telescope in Hawaii. On 25 October 2019, they disentangled the light of five globular clusters in galaxies near the Milky Way. Originally, the globular cluster RBC EXT8 was not on the program, but the researchers had a couple of hours of observing time left and decided to aim their telescope at the cluster. They made two spectroscopic observations of 20 minutes each for the metal content and used three archive images from the Canada-France-Hawaii Telescope to determine the size of the cluster.

The Andromeda Galaxy with the metal-poor globular Soren Larsen (Radboud University, Nijmegen, The cluster RBC EXT8. Credit: ESASky & CFHT. Netherlands) led the research. He kept in touch via Skype with his fellow researchers Jean Brodie (Swinburne University of Technology, Australia, and University of California, Santa Cruz, United An international team of astronomers led by Soren States), Aaron Romanowsky (San Jose State Larsen (Radboud University, Nijmegen, The University, United States, and University of Netherlands) has accidentally discovered a California, Santa Cruz), and Asher Wasserman globular cluster that contains extremely few metals, (University of California, Santa Cruz, United those elements heavier than hydrogen and helium. States). Wasserman operated the telescope in The astronomers had some spare observation time Hawaii from California. and decided to include the globular cluster in the Andromeda galaxy as a bonus. They will publish Larsen says, "Because of the time difference their findings in the journal Science on Friday. between Hawaii and the Netherlands, this was ideal for me. I could look at the stars from my living room Globular clusters usually consist of hundreds of during the day." thousands or millions of ancient stars that move as a group through a galaxy. The metal-poor globular In the future, the researchers hope to find more cluster is called RBC EXT8 and is located in the metal-poor globular clusters and solve the mystery Andromeda galaxy. The stars in the cluster have about their origin. on average 800 times less metals than our sun and are three times lower in metal than the More information: An Extremely Metal-Deficient previous low record in globular clusters. Globular Cluster in the Andromeda Galaxy, Science (2020). DOI: 10.1126/science.abb1970 The astronomers are puzzled, because until now, it doi.org/10.1126/science.abb1970 was thought that large globular clusters had to contain a considerable amount of metals. The new find calls this so-called metallicity floor into question. In addition, the discovery may also have Provided by Netherlands Research School for consequences for the theories about the formation Astronomy of galaxies in the young universe.

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APA citation: Astronomers discover metal-poor globular cluster by chance (2020, October 15) retrieved 2 October 2021 from https://phys.org/news/2020-10-astronomers-metal-poor-globular-cluster-chance.html

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